-더니 vs -았/었더니: Korean Grammar Differences & Usage

-더니 describes something you observed about others or situations in the past and notes a change or outcome, while -았/었더니 shows the result of your own past actions. Learn the key differences to use them naturally in Korean.

1. Definition of -더니 vs -았/었더니 in Korean Grammar

1-1. -더니 (Observation → Change / Sequence)

• Used when the speaker observes someone or something in the past and describes a result, change, or contrast.
• Works with verbs and adjectives.
• Focuses on observed situations or people.
  

1-2. -았/었더니 (Past Action → Result)

• Works only with verbs.
• Shows the outcome of your own completed actions.
• Highlights direct cause-effect relationships.
  

1-3. Quick Comparison Table: -더니 vs -았/었더니

Aspect	-더니	-았/었더니
Subject	Anyone observed	Usually “I”
Tense	Present or past state	Past only
Word Type	Verbs + Adjectives	Verbs only
Meaning	“It was → then…”	“I did → result”
Focus	Observation / sequence / change	Personal experience

2. Conjugation of -더니 vs -았/었더니

2-1. -더니 (Verbs + Adjectives – Base form)

Stem + 더니 (no tense change)

• Verbs: 뛰다 → 뛰더니
• Adjectives: 춥다 → 춥더니

2-2. -았/었더니 (Verbs only – Past tense)

Verb stem + past tense + 았/었더니

• ㅏ/ㅗ vowels: -았더니 (가다 → 갔더니)
• Other vowels: -었더니 (먹다 → 먹었더니)
• 하다 verbs: -했더니 (공부하다 → 공부했더니)
  
  

3. Key Differences in Usage of -더니 vs -았/었더니

3-1. Past Action vs Observed State

Explanation:

• -더니 → Describes something you observed about others or situations in the past, highlighting changes, sequences, or outcomes.
• -았/었더니 → Shows results from your own past actions (direct cause-effect).

Examples:

• 하늘이 맑더니 갑자기 비가 왔어요.
  (The sky was clear, and then it suddenly rained.)
• 아이가 졸리더니 곧 잠들었어요.
• (The child looked sleepy, and eventually fell asleep.)
• 간식을 먹었더니 배가 불러요.
  (I ate a snack, and as a result, I’m full.)
• 운동을 했더니 다리가 아파요.
  (I exercised, and now my legs hurt.)​
  
  

3-2. “I did X” vs “I saw Y happen”

Explanation:

• -더니 → Based on observations of other people or situations, then describing what happened next.
• -았/었더니 → Based on the speaker’s own actions and their direct results.
  

Examples:

• 강아지가 배고프더니 밥그릇을 핥았어요.
  (The puppy looked hungry and licked its food bowl.)
• 친구가 늦잠을 자더니 약속에 늦었어요.
  (My friend overslept and was late for our appointment.)
• 피자를 많이 먹었더니 배가 아파요.
  (I ate too much pizza, and my stomach hurts.)
• 커피를 마셨더니 잠이 깼어요.
  (I drank coffee, and now I’m awake.)
  
  

3-3. Direct Cause vs Sequence/Contrast

Explanation:

• -더니 → Expresses sequence, contrast, or change after observing a situation.
• -았/었더니 → Emphasizes a direct cause-effect relationship.

Examples:

• 바람이 세더니 나뭇잎이 다 떨어졌어요.
  (The wind got strong, and all the leaves fell off.)
• 아이가 울더니 엄마가 오자 금방 웃었어요.
  (The child was crying, but smiled right away when mom came.)
• 밤을 새웠더니 하루 종일 피곤했어요.
  (I stayed up all night, so I was tired all day.)
• 새로운 방법을 시도했더니 문제가 해결됐어요.
  (I tried a new method, and as a result, the problem was solved.)
  
  

3-4. Recalling Events vs Describing Sequences

Explanation:

• -더니 → Used when describing observed sequences or changes in state.
• -았/었더니 → Used when recalling personal past experiences and their results.

Examples:

• 처음에는 어렵더니 연습하니까 쉬워졌어요.
  (At first it was difficult, but after practicing, it became easy.)
• 날씨가 흐리더니 갑자기 해가 나왔어요.
  (The weather was cloudy, and then the sun suddenly came out.)
• 시험 공부를 열심히 했더니 성적이 올랐어요.
  (I studied hard for the exam, and my score improved.)
• 음식을 천천히 먹었더니 소화가 잘됐어요.
  (I ate slowly, and my digestion improved.)
  

4. Practice Exercises for -더니 vs -았/었더니

Fill in the blanks with the correct form of -았/었더니 or -더니.

1. 어제 늦게 (자다) ________ 오늘 아침에 일어나기 힘들었어요.
   (I went to bed late yesterday, and as a result, it was difficult to wake up this morning.)
   
   
2. 날씨가 (추워지다) ________ 사람들이 두꺼운 옷을 입기 시작했어요.
   (The weather became cold, so people started wearing thick clothes.)
   
   
3. 열심히 (공부하다) ________ 시험 결과가 좋았어요.
   (I studied hard, and as a result, my test results were good.)
   
   
4. 처음에는 (어색하다) ________ 시간이 지나면서 편해졌어요.
   (At first it was awkward, but as time passed, it became comfortable.)
   
   
5. 약을 (먹다) ________ 두통이 사라졌어요.
   (I took medicine, and as a result, my headache disappeared.)
   
   
6. 친구가 (바쁘다) ________ 결국 약속을 취소했어요.
   (My friend was busy, so they eventually canceled our appointment.)
   
   
7. 새로운 운동을 (시작하다) ________ 몸이 건강해졌어요.
   (I started a new exercise routine, and as a result, my body became healthier.
   
   
8. 아이가 (졸리다) ________ 결국 소파에서 잠들었어요.
   (The child was sleepy, and eventually fell asleep on the sofa.)
   
   
9. 영화를 (보다) ________ 생각이 많아졌어요.
   (I watched a movie, and as a result, I had a lot to think about.)
   
   
10. 경제가 (어려워지다) ________ 많은 회사들이 문을 닫았어요
    (The economy became difficult, and many companies closed down.)
    
    

Answers

1. 잤더니
2. 추워지더니
3. 공부했더니
4. 어색하더니
5. 먹었더니
6. 바쁘더니
7. 시작했더니
8. 졸리더니
9. 봤더니
10. 어려워지더니
    
    

5. FAQ: -더니 vs -았/었더니

Q1. Can I use -더니 for my own past actions?
No. In Korean grammar, -더니 is only used for observed events, not your own completed actions.

Q2. Does -았/었더니 work with adjectives?
No. -았/었더니 works only with verbs to indicate completed actions; adjectives cannot be used in this pattern.

Q3. How do I know which to use when describing results?
In Korean grammar, use -았/었더니 for your personal past actions and use -더니 for observed events that lead to a change or contrast.

Q4. Can -더니 indicate unexpected results?
Yes. -더니 often emphasizes sequence or contrast, sometimes showing a surprising outcome from what was observed.

Q5. Are -더니 and -았/었더니 interchangeable?
No. -더니 is for observations, while -았/었더니 is for your own completed actions, and they cannot be used interchangeably.

6. Key Points to Remember for -더니 vs -았/었더니

• -았/었더니 → verbs only, personal past actions, direct cause-effect.
• -더니 → verbs & adjectives, observed events, sequences, or contrasts.
• -았/었더니 → recalling personal events; -더니 → describing observed sequences.
• -아/었더니 always refers to past actions; -더니 can refer to past or present states
  
  

7. Related Korean Grammar Points Comparing -더니 vs -았/었더니

If you’re learning -더니 or -았/었더니, you may also want to compare:

• -(으)ㄹ래요? vs -(으)ㄹ까요?
• -아/어 놓다 vs -아/어 두다
• -기는 하지만’ vs -지만
• -(으)ㄹ게요 vs -(으)ㄹ 거예요
• -아/어 봤자 vs -아/어도
  
  

8. Related Korean Grammar Points and Patterns for -더니 vs -았/었더니

Here’s a set of five related Korean grammar patterns that naturally connect with -더니 vs -았/었더니:

• -(으)ㄹ게요 (I’ll…) – Speaker’s Decision
  Indicates a decision made by the speaker, often in response to the listener.
• -(으)ㄹ까요? (Shall we…?) – Polite Suggestion / Speculation
  Used to propose actions or ask for suggestions politely.
• -고 나서 (After doing…) – Sequence of Actions
  Shows that one action is completed before the next starts.
• -아/어 보니 (After trying…) – Realization / Discovery
  Used when sharing a discovery based on personal experience.
• -다가 (While / Then) – Interruption or Sequence
  Used to describe an action interrupted by another action or a sequence of events.